A poorly working air-conditioning system is more likely to fail during hot weather. You should inspect the air conditioning system before the summer begins to ensure it is working properly.

Vehicle air conditioners are mini- refrigerators that both cool and dehumidify the air entering the passenger compartment. Like a kitchen "fridge," a refrigerant is used to cool the air and carry away heat, which requires both an adequate refrigerant level and a properly circulating system. Vehicle air conditioners should be serviced annually.

Keep an eye out for these warning signs that may indicate problems:

The system doesn't cool to the temperature desired

A musty smell comes out of the vents when operating

There is water on the vehicle floor

The air conditioner or engine make loud noises or run roughly whenever the air conditioner is running

Engine overheats when the air conditioner is on

During servicing, the technician will examine the belts and check for hose leaks. Low refrigerant levels are topped off with R-134a, an environmentally friendly product that replaced R-12 ("Freon") in the late 1990s. Vehicles manufactured before 1995, which still use Freon (which is dangerous to the earth's important ozone layer), can be converted to use R-134a, which is also less expensive than Freon.

During servicing, the technician may change the cabin air filter, which acts to remove pollen, dust, cigarette smoke and smog from the inside of the vehicle. A clogged filter allows bacteria (mold) to grow in the heating and ventilation system, which inhibits airflow and could affect passengers' health. The cabin air filter should be replaced once a year or every 15,000 miles. And twice as often if you are a smoker or you drive in an area with high pollen levels (ie farmland).

The air conditioner will increase a car's fuel consumption, but so will driving with the windows down, due to increased drag. When its not too warm outside, you can conserve some fuel by turning off the air conditioner while driving in slow traffic.

To summarize:

Don't drive at high speeds with windows down, to reduce draft and therefore fuel consumption

replace the cabin air filter at least every15,000 miles

Turn off air conditioning on cooler days while driving in slower traffic